Thus \(r=\)constant line is a hyperbola joining \(i^{\pm }\)  and it can be drawn w.r.t any of the the above Kruskal coordinates, shown in the Carter-Penrose diagram of the maximally extended SdS spacetime in the following sections. Once we place this hyperbola or the thermal opaque membrane, modes of the either side of this wall cannot penetrate it and remain in their respective regions. So this effective potential can be think of a natural realisation of the thermally opaque membrane. Now, we shall be discussing the island proposal [1]} to calculate the entanglement entropy of Hawking radiation.
